A conventional direct-drive type washing machine is disclosed in Korean Patent Registration Publication No. 10-0438616 on Jun. 23, 2004, which includes: a casing; an outer tub that is disposed inside the casing; a washing tub that is rotatably accommodated in the inside of the outer tub; a pulsator that is rotatably mounted on the bottom surface of the washing tub to enable a relative motion; a washing motor that is mounted at the bottom of the outer tub for generating a rotational force; a drive shaft assembly that is coupled to a rotor of the washing motor and transfers a rotational force of the washing motor to the washing tub or the pulsator; a washing tub rotating shaft whose one end is fixedly coupled with the washing tub; a pulsator rotating shaft that is inserted into the washing tub rotating shaft and whose one end is fixed to the pulsator; a rotating shaft coupling unit that couples the drive shaft assembly with the washing tub rotating shaft and the pulsator rotating shaft in a gear-driving type, and thus transfers the rotational force of the washing motor to the washing tub rotating shaft and the pulsator rotating shaft; a coupling unit that can move along the axial direction of the drive shaft assembly and that is coupled to the washing tub rotating shaft or the pulsator rotating shaft; a coupling unit lifting lever that lifts the coupling unit in the axial direction; and a lifting lever drive unit that is coupled with the coupling unit lifting lever and thus lifts up or pulls down the coupling unit lifting lever.
The rotating shaft coupling unit is configured to include a planetary gear set to slow down the pulsator rotating shaft and the washing tub rotating shaft, to thus play a role of transmitting power to one or both of the pulsator rotating shaft and the washing tub rotating shaft.
In addition, the coupling unit, the coupling unit lifting lever, and the lifting lever drive unit are configured to form a clutch device that transmits the rotational force of the washing motor to the pulsator rotating shaft, or both of the pulsator rotating shaft and the washing tub rotating shaft.
However, the direct-drive type washing machine according to the conventional art requires the coupling unit, the coupling unit lifting lever, and the lifting lever drive unit, in order to transmit the rotational force of the washing motor to both or one of the pulsator rotating shaft and the washing tub rotating shaft, to thereby increase the manufacturing cost, and make the structure become complicated.
Further, since the pulsator and the dehydrating tub do not rotate in different directions at the same time, it has a problem that performance of the washing machine is degraded.